Traditionally, an individual establishes his or her identity by using passports and identity cards or by remembering and using passwords and/or personal identification numbers (PINs) to identify himself or herself and to gain access to secure areas, data, or systems. Unfortunately, passports and identity cards can be lost, duplicated, or stolen. PINs and passwords can easily be forgotten, observed, or intentionally shared with others. As a result, major security issues have arisen for both individuals and corporations. Individuals are concerned with identity theft and privacy. Corporations are concerned with theft of data, intellectual property, and trade secrets. Both individuals and corporations continue to seek new methods and systems for identification and authentication.